Prostanoids (PG) are important signaling molecules that regulate many physiological and pathological processes. PG mediate pain, fever, inflammation and are involved in the development of a broad range of clinical disorders including cancer, inflammation, neurodegenerative diseases, central nervous system injury, and neuropsychiatric conditions. However, the mechanism that regulates brain PG levels is poorly understood. Our long-term goal is to understand the mechanism underlying the regulation of brain PG levels and to outline potentially new therapeutic targets for drugs used in the treatment of a wide variety of neuropathophysiological conditions. The objective of this application is to elucidate the mechanisms accounting for the immediate, rapid increase (<1 min) in brain prostanoids upon stimulation. In this application, we hypothesize a novel pathway for PG release. Our Central Hypothesis is that the rapid increase in prostanoid mass occurs via mobilization of a rapidly releasable pool of preformed PG found esterified onto phospholipids. Our findings presented in the Preliminary Studies support this hypothesis. We found that: 1. PG are esterified onto phospholipids [Note these were not isoprostanes];2. esterified PG are rapidly released upon stimulation in vivo;3. PG stored on phospholipids are derived from COX1/2;4. exogenously added PG are esterified onto cellular phospholipids;5. arachidonic acid (20:4n-6) release is not required for this initial increase in PG mass during the inflammation response. The hypothesized novel pathway for prostanoid release addresses some of the contradictions associated with the traditional pathway of PG release and is more consistent with the known rapid formation of PG in brain. Importantly, our proposed novel pathway refers to the rapid increase in PG mass increase at early phase of tissue response upon stimulation, and does not argue against the role of traditional pathway at the late phases of tissue response. However, because the initial rapid increase in PG mass may trigger consequent phases of tissue response, the proposed novel pathway for PG release is undoubtedly linked to the later phases of tissue injury response with regards to PG formation. The central hypothesis will be tested by the following specific aims: Specific Aim 1: Determine the capacity of brain cells and tissue for PG storage in esterified form;Specific Aim 2: Determine enzymatic systems responsible for PG release from phospholipid storage pool;The proposed work is innovative because it examines a novel pathway for PG release from preformed pool esterified onto phospholipids that has not been previously addressed by others. These results will be significant because the successful completion of the project will enhance the current view regarding the regulation of brain PG levels and will reveal a new function for phospholipids in PG release. Also, it will outline potentially new therapeutic targets for drugs used in the treatment of a wide variety of neuropathophysiological conditions and will enhance our understanding of the mechanisms underlying these conditions. PUBLIC HEALTH RELEVANCE: The relevance of our proposed work is that it examines a novel mechanism for a rapid increase of brain prostanoid levels through prostanoid release from preformed pool esterified onto phospholipids that has not been previously addressed by others. This is important because of the association of prostanoids with a large number of neurodegenerative diseases. These results will be significant because they will enhance the current traditional view regarding the regulation of brain prostanoid levels, outline potentially new therapeutic targets for drugs used in the treatment of a wide variety of neuropathophysiological conditions, and enhance our understanding of the mechanisms underlying these conditions.